1. Field of the Invention
The present invention relates to a data path for a maskless lithography apparatus, and in particular to a data path for transferring pattern data for control of a plurality of charged particle beamlets.
2. Description of the Related Art
A design for an integrated circuit is typically represented in a computer-readable file containing data for patterning each layer of the integrated circuit onto a silicon wafer. For lithography machines which use masks, this pattern data is typically used to manufacture a mask or set of masks which are then used by the lithography machine for pattering the wafer. For maskless lithography machines, the pattern data file is electronically processed to put it into a format suitable for controlling the lithography machine. For charged particle lithography machines, the pattern data file is converted into a set of data signals for controlling the charged particle beams used in the lithography process.
A data path is typically used to transmit the pattern data from an off-line data processing and storage system to the lithography machine. A very large quantity of data is required to represent the pattern for the current and near future generations of integrated circuit, necessitating a data path having a very high transmission capacity. This very high transmission capacity may be achieved by using a very large number of channels and very high data transmission rates per channel. However, this greatly increases the cost of the data path and it becomes a major component of the overall cost of a charged particle lithography machine.
Due to the very large number of channels, it is likely that a portion of the data path channels will suffer a failure or degradation in capacity and should be not be used. Moreover, designing an efficient connection system between such a large number of channels and the lithography machine is difficult, particularly in view of the need to transmit the data with very high reliability while avoiding use of failed transmission channels.